In addition to previous Summerfest shows, the Las Vegas band's December stop at the Rave was its eighth at the venue in a decadelong career. Pair that with a large crowd that skewed young — a large portion clad in Panic! T-shirts, belting out lyrics — and the band's placement ahead of Weezer on their co-headlining tour's stop at the Marcus Amphitheater seemed like a misstep.

But Brendon Urie, the sole permanent member and creative lifeblood of Panic!, explained the arrangement Saturday night. "I learned to play drums, guitar and sing to their blue album and 'Pinkerton,'" he said, adding he spends each night stalking the band backstage. "I'm losing my (expletives)."

Influences aside, none of that stopped Urie from setting a high bar of energy, bravado, expressive passion, and even backflips, across the nonstop fevered pace of the 75-minute set. Dressed in a satiny blue suitcoat over a leopard print shirt, he sashayed, flipped his gold microphone in the air, shrieked and wore expressions as big as his voice in front of his six-piece band on the opening "Don't Threaten Me With a Good Time."

Removing his shirt to wails of pleasure, Urie hopped behind a drum set in "Crazy = Genius" and dueled drummer Dean Pawlovich. On the band's stunningly spot-on cover of "Bohemian Rhapsody," Urie was a sweat-dripping, ever-confident, Freddie Mercury-channeling vision of modern rock 'n' roll excess. With the combustive shouts for the frenetic set-closing "Victorious," no one could blame the exuberant crowd for being spent.

But the masses were a bit muted — and a few seats were empty — for Weezer's arrival and the opening "California Kids" from its new self-titled album. As streamers rained down on the pit in a swelling crescendo, the band didn't seem to notice — although physical expression has never been one of frontman Rivers Cuomo's attributes.

After diverting from their alternative rock roots to a modern pop sound in the mid-2000s that disenfranchised some hardcore fans, the quartet has worked to recapture their essence on the past two albums.

In concert, the Beach Boys-influenced classic pop of the new disc framed the set both audibly in the understated irony of "Jacked Up" and syncopated brooding of "Thank God For Girls," and visually in the beachfront staging. The new songs tended to flatten the crowd, although the expletive-laden hyper-patriotic non-album single "I Love the USA" elicited chants in its first public performance.

Turns out the best way to regain the band's vitality came through plumbing its catalog. "Hash Pipe" throbbed with thundering intensity as beach balls bounced over the crowd. "My Name is Jonas" thrashed in Cuomo's voice. "Undone (The Sweater Song)" found the band surrounding Pat Wilson's drum set, before Cuomo bobbed his head and lurched into an inspired guitar breakdown. By the main set's close, the remaining fans were all-in.